It is common in our daily life to adjust the value of an output voltage signals by using a manipulating device, such as the variable resistor. Based on the type of operation, the variable resistors can be sorted as rotating-type variable resistors and slide-type variable resistors.
FIG. 1 is an explosive view of a conventional slide-type variable resistor. As shown, the variable resistor PA100 includes a shell PA1, two fixing parts PA2, two guiding rods PA3, a brush base PA4, and a circuit base PA5. Each of the two fixing parts PA2 has tow positioning grooves PA21. The brush base PA4 has a main body PA41, two brushes PA42, and a manipulating part PA43. The two sliding rods PA3 penetrate two through holes PA411 of the main body PA41 respectively and located in the positioning grooves PA21 of the two fixing parts PA2. Then, the brush base PA4 together with the two sliding rods PA3 and the two fixing parts PA2 are positioned in the shell PA1 with the manipulating part PA43 extending outward from the position restriction hole of the shell PA1 such that the user can operate the manipulating part PA43 to control the position the brushes PA42 to contact the resistance circuit on the circuit base PA5 so as to generate different output voltage.
As mentioned, because the brush base PA4 is designed to move along the sliding rods PA3, which are merely supported by the fixing parts PA2 at the opposite ends of the sliding rod PA3, the sliding rods PA3 might be easily escaped from the positioning groove PA21 due to improper operation which may damage the variable resistor PA100 or make the variable resistor PA100 inoperative.